Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
  • H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
  • H01M8/065—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants by dissolution of metals or alloys; by dehydriding metallic substances
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
  • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
  • C01B3/06—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents
  • C01B3/065—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of inorganic compounds containing electro-positively bound hydrogen, e.g. water, acids, bases, ammonia, with inorganic reducing agents from a hydride
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D15/00—Lithium compounds
  • C01D15/02—Oxides; Hydroxides
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
  • H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
  • H01M8/0656—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants by electrochemical means
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
  • C01B2203/06—Integration with other chemical processes
  • C01B2203/066—Integration with other chemical processes with fuel cells
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M2008/1095—Fuel cells with polymeric electrolytes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Definitions

• the invention relates to a hydrogen production method, a hydrogen production system used to implement the hydrogen production method, and a fuel cell system incorporating the hydrogen production system.
• a fuel cell is constituted of an electrolyte layer and a pair of electrodes and causes electrochemical reactions.
• the electrochemical reactions at each fuel cell generate electric power, and this electric power is output.
• various fuel cell systems household cogeneration systems and solid-polymer type fuel cell systems typically used for automobiles, etc., (will be referred to as "PEFCs") use hydrogen-containing gas and oxygen-containing gas. Therefore, in order to put such PEFCs to practical use, reliable hydrogen production technologies and hydrogen storage technologies are essential.
• the hydrogen storage technologies that have been proposed so far include compressing hydrogen gas and then storing it in a high-pressure hydrogen tank, storing liquid hydrogen in a liquid hydrogen tank, and storing a hydrogen adsorption material adsorbing hydrogen (will be referred to as "hydrogen production material' * where necessary) in a tank.
• a high-pressure hydrogen tank a large volume of the high-pressure hydrogen tank makes it difficult to provide a compact system, and it also requires high pressurization energy to increase the pressure of hydrogen up to a desired high level, which is not efficient.
• a liquid hydrogen tank there are some problems.
• JP- A-2002-526658 describes a technology related to hydrogen adsorption materials.
• This publication proposes a lithium group hydrogen compound having a high hydrogen capacity and capable of increasing the amount of hydrogen irreversibly at a high rate.
• Japanese Patent Application Publication No. 2005-154232 describes a technology related to hydrogen storage materials.
• the hydrogen storage material described in this publication is constituted of hydrogen compounds of metal and ammonia, and hydrogen is produced through the reaction between the hydrogen compounds of metal and the ammonia.
• JP-A-2006- 182598 describes a technology related to hydrogen production
• This publication proposes a hydrogen production system that reuses by-products by reacting them with non-separated hydrogen to produce organic hydrides.
• the invention provides a hydrogen production method that is useful for realizing a sustainable hydrogen society, a hydrogen production system adapted to implement the hydrogen production method, and a fuel cell system incorporating the hydrogen production system.
• the first aspect of the invention relates to a hydrogen production method including: a first process in which nitrogen compounds of metal and water are reacted to produce ammonia and hydroxide of the metal; a second process in which hydrogen compounds of a metal and the ammonia produced in the first process are reacted; and a third process in which hydrogen compounds of a metal and the hydroxide of the metal produced in the first process are reacted.
• hydrogen can be produced with a small amount of energy.
• hydrogen is produced using ammonia, and the ammonia is produced in the first process. Therefore, it is not necessary to store ammonia for hydrogen production in advance.
• the amide compounds of the metal that are produced together with hydrogen in the second process are reformed into hydrogen compounds of the metal, and the oxide of the metal produced in the third process is reformed into nitrogen compounds of the metal, and such reforming of the amide compounds and metal oxide does not produce waste.
• the hydrogen production method of the first aspect of the invention provides a high hydrogen capacity and requires only liquid water, nitrogen compound of the metal in solid or liquid state, and hydrogen compounds of the metal in solid or liquid state as materials for producing hydrogen.
• the hydrogen production method of the first aspect of the invention enables downsizing hydrogen production systems.
• the hydrogen production method of the first aspect of the invention may be such that the hydrogen compounds of the metal are hydrogen compounds of lithium or hydrogen compounds of magnesium.
• the hydrogen production method of the first aspect of the invention may be such that the nitrogen compounds of the metal are nitrogen compounds of lithium or nitrogen compounds of magnesium.
• the amount of energy for producing hydrogen can be further reduced, and the system with the substances fo ⁇ producing hydrogen can be downsized more easily, and the reforming of the hydrogen compounds of the metal or the reforming of the nitrogen compound of the metal, which will be described later, can be facilitated.
• the hydrogen production method of the first aspect of the invention may be such that the reaction between the hydrogen compounds of the metal and the ammonia in the second process is performed in the presence of TiCb (Titanium (DO) chloride).
• TiCb Tianium (DO) chloride
• the hydrogen production method of the first aspect of the invention may be such that the reaction between the hydrogen compounds of the metal and the hydroxide of the metal in the third process is performed in the presence of TiCb.
• the hydrogen production method of the first aspect of the invention may be such that the hydrogen compounds of the metal are produced through reaction between amide compounds of the metal produced in the second process and hydrogen.
• the hydrogen compounds of the metal can be produced using the amide compounds of the metal produced in the second process, that is, the hydrogen compounds of the metal used for the hydrogen production method can be regenerated.
• the hydrogen production method of the first aspect of the invention may be such that the nitrogen compounds of the metal are produced through reaction between the metal obtained from the oxide of the metal produced in the third process and nitrogen.
• the nitrogen compounds of the metal used in the hydrogen production method can be regenerated.
• the hydrogen production method of the first aspect of the invention may be such that the metal reacted with the nitrogen is obtained by reducing the oxide of the metal through moHen-salt electrolysis.
• a hydrogen production system that implements the hydrogen production method according to the first aspect of the invention, may have: a first tank storing the nitrogen compounds of the metal; a second tank storing the water; and a third tank and a fourth tank each storing the hydrogen compounds of the metal; separating means for separating the ammonia produced in the first process.
• the first process may be performed by delivering the water in the second tank to the first tank
• the second process may be performed by delivering the ammonia separated by the separating means to the third tank after the first process
• the third process may be performed by delivering the hydroxide of the metal Ln the first tank to the fourth tank after the first process.
• the first process can be performed by delivering the water stored in the second tank to the first tank
• the second process can be performed by delivering the ammonia produced through the reaction between the nitrogen compounds of the metal and the water in the first tank to the third tank storing the hydrogen compounds of the metal
• the third process is performed by delivering the hydroxide of the metal produced in the first process (the hydroxide of the metal and the water) to the fourth tank storing the hydrogen compounds of the metal.
• a hydrogen production system that implements the hydrogen production method according to the first aspect of the invention may have: a first tank storing the nitrogen compounds of the metal; a second tank storing the water; and a third tank and a fourth tank each storing the hydrogen compounds of the metal; separating means for separating the ammonia produced in the first process; a fifth tank storing the ammonia separated by the separating means; and flow-controlling means for controlling movement of fluid between the first tank and the fourth tank.
• the first process may be performed by delivering the water in the second tank to the first tank
• the second process may be performed by delivering the ammonia from the fifth tank to the third tank after the first process, so that an opening is formed at the flow-controlling means due to heat generated by the second process
• the third process may be performed by delivering the hydroxide of the metal and the water in the first tank to the fourth tank through the opening after the first process.
• the first process can be performed by delivering the water in the second tank to the first tank
• the second process can be performed by delivering the ammonia produced through the reaction between the nitrogen compounds of the metal and the water in the first tank and separated to the fifth tank by the separating means to the third tank storing the hydrogen compounds of the metal
• the third process can be performed by delivering the hydroxide of the metal produced in the first process to the fourth tank via the opening formed due to the heat generated in the second process.
• the metal may be lithium or magnesium.
• T1CI 3 may be additionally stored in the third tank.
• T1CI 3 may be additionally stored in the fourth tank.
• the reaction rate of the hydrogen producing reactions increases, and thus the yield of hydrogen increases, and the temperature required to ensure smooth progression of the hydrogen producing reactions decreases.
• the hydrogen produced by the hydrogen production system may be delivered to the fuel cell, and the water produced at the fuel cell may be delivered to the second tank.
• the hydrogen produced by the hydrogen production system is delivered to the fuel cell, and the fuel cell operates on the hydrogen thus delivered. Further, in this fuel cell system, because the water produced at the fuel cell is delivered to the second tank of the hydrogen fuel cell system, the water produced at and then discharged from the fuel cell can be effectively used.
• FIG 1 is a flowchart illustrating the processes of a hydrogen production method according to the first example embodiment of the invention
• FIG 2 is a flowchart illustrating a procedure of a hydrogen production method according to the second example embodiment of the invention
• FIG. 4A and FIG 4B are view schematically showing a container (third tank) used in the first example embodiment of the invention to contain lithium amide;
• FIG 5 is a view schematically showing a hydrogen production system according to the third example embodiment of the invention and a hydrogen production system according to the fifth example embodiment of the invention
• FIG 6 is a view schematically showing a hydrogen production system according to the fourth example embodiment of the invention and a hydrogen production system according to the sixth example embodiment of the invention.
• FIG 7 is a view schematically showing a fuel cell system according to the seventh example embodiment of the invention.
• the flowchart of FlG 1 illustrates the processes of a hydrogen production method according to the first example embodiment of the invention (this method will hereinafter be referred to as "first hydrogen production method” where necessary).
• the first hydrogen production methods includes the first process (SIl), the second process (S12), and the third process (S13). Hydrogen is produced through these processes SIl to S13.
• lithium nitride (LbN) is reacted with water (H 2 O) as represented by the following reaction formula (1) indicated below.
• the reaction represented by this reaction formula (1) above is a heat-generating reaction that is caused by, for example, contacting solid lithium nitride (Li 3 N) with liquid water (H 2 O), and the reaction can progress at a room temperature.
• the ammonia (NH3) produced in the first process SIl is used in the second process S12 and the lithium hydroxide (LiOH) produced in the first process SIl is used in the third process S13 as follows.
• the reaction represented by this reaction formula (2) above is a heat-generating reaction that is caused by, for example, contacting gaseous ammonia (NH 3 ) with solid lithium hydride (UH), and the reaction can progress at a room temperature.
• hydrogen is produced in the second process S 12.
• the lithium amide (UNH 2 ) produced in the second process S 12 is reformed into lithium hydride (UH) using a metal hydrogen compound production method (lithium hydride production method) according to the invention as will be described in detail later.
• the lithium hydroxide (UOH) is reacted with lithium hydride (LiH) as represented by the reaction formula (3) indicated below.
• the reaction represented by the reaction formula (3) above is a heat-generating reaction that is caused by, for example, contacting solid lithium hydroxide (LiOH) with solid lithium hydride (UH), and the reaction can progress at a room temperature.
• hydrogen is produced also in the third process S13.
• the lithium oxide (U 2 O) produced in the third process S13 is reformed into lithium nitride (U 3 N) using a metal nitrogen compound production method (lithium nitride production method) according to the invention as will be described in detail later.
• the reaction of the third process S13 occurs between solid and solid as mentioned above, the reaction efficiency may be low as compared to the first process SIl and the second process S 12.
• the following methods are preferably used to improve the reaction efficiency of the third process S13: (a) Solid IiOH is reacted with solid LiH milled into particles measuring several tens run or so in size; (b) Solid LiOH milled into particles measuring several tens nm or so in size is reacted with solid LiH milled into particles measuring several tens nm or so in size; and (c) LiOH dissolved in liquid (e.g., pure water) is reacted with solid IiH.
• liquid e.g., pure water
• the first hydrogen production method hydrogen is produced through the heat-generating reactions represented by the reaction formulas (1) to (3) above.
• hydrogen can be produced without using a large amount of heat, and further each reaction progresses at a room temperature.
• the first hydrogen production method enables producing hydrogen with a small amount of energy.
• IJ 3 N, H ⁇ O, and LiH are used to produce hydrogen in the first hydrogen production method.
• L1 3 N and LiH can be regenerated using a method described later, and H 2 O can be obtained from the water produced at fuel cells, for example.
• the first hydrogen production method enables producing hydrogen from regenerated IJ 3 N and LiH and thus is useful for realizing a sustainable hydrogen society.
• the first hydrogen production method further, because the NH 3 used in the second process S12 is produced in the first process SIl, it is not necessary to store NHb for producing hydrogen, that is, a necessary amount of NH 3 can be obtained by reacting U 3 N with H 2 O.
• the first hydrogen production method eliminates the necessity of storing NH 3 in advance and thus simplifies the system for preparing NH 3 .
• the hydrogen capacity achieved in the hydrogen productions in the second process Sl 2 and the third process S 13 is 6.6 to 11.0 mass%, which is high as compared to the hydrogen capacities achieved by the majority of the hydrogen production methods proposed so far.
• the first hydrogen production method enables producing a large amount of hydrogen from a small amount of hydrogen production materials.
• the first hydrogen production method is not limited to this feature.
• the third process S 13 may be performed after the second process S12, or the second process S12 may be performed after the third process S13.
• the third process S13 is preferably performed after the second process S12.
• the second process S 12 may be performed in any manner as long as the ammonia (NH 3 ) produced in the first process SIl can be properly reacted with lithium hydride (LiH), the ammonia (NH 3 ) produced in the Orst process SIl is preferably reacted with lithium hydride (UH) in the presence of TiCb that catalyzes the reaction represented by the reaction formula (2).
• the reaction rate of the reaction represented by the reaction formula (2) increases, and thus the yield of hydrogen obtained from the reaction represented by the reaction formula (2) improves.
• the third process S13 may be performed in any manner as long as the lithium hydroxide (LiOH) produced in the first process SIl can be properly reacted with lithium hydride (LiH), preferably, the lithium hydroxide (LiOH) is reacted with lithium hydride (LiH) in the presence of TiCb that catalyzes the reaction represented by the reaction formula (3).
• the reaction rate of the reaction represented by the reaction formula (3) increases, and thus the yield of hydrogen obtained from the reaction represented by the reaction formula (3) improves.
• the reaction represented by the reaction formula (3) needs to be performed at a high temperature of approx.
• the flowchart of FIG 2 illustrates a procedure of a hydrogen production method according to the second example embodiment of the invention (this method will hereinafter be referred to as "second hydrogen production method" where necessary).
• magnesium is used to produce hydrogen.
• the processes corresponding to the first to third processes of the first hydrogen production method will be referred to as “the first reaction process (S21)”, “the second reaction process (S22)”, and “the third reaction process (S23)", respectively. That is, in the second hydrogen production method, hydrogen is produced through the first reaction process S21, the second reaction process S22, and the third reaction process S23.
• the first reaction process S21 magnesium nitride (Mg 3 Na) is reacted with water (H 2 O) as represented by the reaction formula (4) shown below.
• the reaction represented by the reaction formula (4) above is a heat-generating reaction that is caused by, for example, contacting solid magnesium nitride (Mg 3 N 2 ) with liquid water (H 2 O), and the reaction can progress at a room temperature.
• the ammonia (NH 3 ) produced in the first reaction process S21 is used in the second reaction process S22 and the magnesium hydroxide (Mg(OH) 2 ) produced in the first reaction process S21 is used in the third reaction process S23 as follows.
• the reaction represented by the reaction formula (5) above is a heat-generating reaction that is caused by, for example, contacting gaseous ammonia (NH 3 ) with solid magnesium hydride (MgH 2 ), and the reaction can progress at a room temperature.
• gaseous ammonia NH 3
• MgH 2 solid magnesium hydride
• hydrogen is produced in the second reaction process S22.
• the magnesium amide (Mg(NH 2 ) 2 ) produced in the second reaction process S22 is reformed into magnesium hydride (MgH 2 ) using a metal hydrogen compound production method (magnesium hydride production method) according to the invention as will be described in detail later.
• the magnesium hydroxide (Mg(OH ⁇ ) produced in the second reaction process S21 is reacted with magnesium hydride (MgH 2 ) as represented by the reaction formula (6) indicated below.
• the reaction represented by the reaction formula (6) above is a heat-generating reaction that is caused by, for example, contacting solid magnesium hydroxide (Mg(OH) 2 ) with solid magnesium hydride (MgH 2 ), and the reaction can progress at a room temperature.
• Mg(OH) 2 solid magnesium hydroxide
• MgH 2 solid magnesium hydride
• hydrogen is produced also in the third reaction process S23, and the magnesium oxide (MgO) produced in the third reaction process S23 is reformed into magnesium nitride (Mg 3 N 2 ) using a metal nitrogen compound production method (magnesium nitride production method) according to the invention as will be described in detail later.
• the reaction efficiency may be low as compared to the first reaction process S21 and the second reaction process S22.
• the following methods are preferably used to improve the reaction efficiency in the third reaction process S23: (a) Solid Mg(OH) 2 is reacted with solid MgH 2 milled into particles measuring several tens nm or so in size; (b) Solid Mg(OH) 2 milled into particles measuring several tens nm or so in size is reacted with solid MgH 2 milled into particles measuring several tens tun or so in size; and (c) Mg(OH) 2 dissolved in liquid (e.g., pure water) is reacted with solid MgH 2 .
• liquid e.g., pure water
• the reactions in the methods (a) and (b) occur between solid and solid, because Mg(0H) 2 is milled into particles or MgH 2 and Mg(OH) 2 are both milled into particles, the contact area between MgH 2 and Mg(OH) 2 is large and the reaction efficiency is high. Further, because the reaction in the method (c) occurs between dissolved Mg(OH) 2 and solid MgH 2 , the reaction efficiency is high. By the method (c), the reaction efficiency can be improved especially easily.
• the second hydrogen production method hydrogen is produced through the heat-generating reactions represented by the reaction formulas (4) to (6) above.
• hydrogen can be produced without using a large amount of heat, and further each reaction progresses at a room temperature.
• the second hydrogen production method enables producing hydrogen with a small amount of energy.
• Mg 3 N 2 , H 2 O, and MgH 2 are used to produce hydrogen in the second hydrogen production method.
• Mg 3 N 2 and MgH 2 can be regenerated using a method described later, and H 2 O can be obtained from the water produced at fuel cells, for example.
• the second hydrogen production method enables producing hydrogen from regenerated Mg 3 N 2 and MgH 2 and thus is useful for realizing a sustainable hydrogen society.
• the second hydrogen production method further, because the NH 3 used in the second reaction process S22 is produced in the first reaction process S21, it is not necessary to store NH 3 for producing hydrogen, that is, a necessary amount of NH 3 can be obtained by reacting Mg 3 N 2 with H 2 O. As such, the first hydrogen production method eliminates the necessity of storing NH 3 in advance and thus simplifies the system for preparing NH 3 .
• the hydrogen capacity achieved in the hydrogen productions in the second reaction process S22 and the third reaction process S23 is 4.6 to 11.0 raass%, which is high as compared to the hydrogen capacities achieved by the majority of the hydrogen production methods proposed so far.
• the second hydrogen production method enables producing a large amount of hydrogen from a small amount of hydrogen production materials.
• the second reaction process S22 and the third reaction process S23 are performed at the same time in the example illustrated in FIG 2, the second hydrogen production method is not limited to this feature.
• the third reaction process S23 may be performed after the second reaction process S22, or the second reaction process S22 may be performed after the third reaction process S23.
• the third reaction process S23 is preferably performed after the second reaction process S22.
• the second reaction process S22 may be performed in any manner as long as the ammonia (NH 3 ) produced in the first reaction process S21 can be properly reacted with magnesium hydride (MgH 2 ), the ammonia (NH 3 ) produced in the first reaction process S21 is preferably reacted with magnesium hydride (MgH 2 ) in the presence of T1CI 3 that catalyzes the reaction represented by the reaction formula (5).
• the reaction rate of the reaction represented by the reaction formula (5) increases, and thus the yield of hydrogen obtained from the reaction represented by the reaction formula (5) improves.
• the third reaction process S23 may be performed in any manner as long as the magnesium hydroxide (Mg(0H) 2 ) produced in the first reaction process S21 can be properly reacted with magnesium hydride (MgH 2 ).
• the magnesium hydroxide (Mg(OH) 2 ) produced in the first reaction process S21 is reacted with magnesium hydride (MgH 2 ) in the presence of TiCl 3 that catalyzes the reaction represented by the reaction formula (6).
• the reaction rate of the reaction represented by the reaction formula (6) increases, and thus the yield of hydrogen obtained from the reaction represented by the reaction formula (6) improves.
• Tl the temperature required to ensure smooth progression of the reaction represented by the reaction formula (6) in the absence of TiCb
• T2 the temperature required to ensure smooth progression of said reaction in the presence of T1CI3
• Tl the temperature required to ensure smooth progression of said reaction in the presence of T1CI3
• Tl the temperature required to ensure smooth progression of said reaction in the presence of T1CI3
• Tl the temperature required to ensure smooth progression of said reaction in the presence of T1CI3
• FIG 3 schematically illustrates a lithium hydride production method employed in the first example embodiment of the invention.
• the lithium amide (Uh[H 2 ) produced in the second process S12 of the first hydrogen production method is reacted with hydrogen (H 2 ), whereby the reverse reaction of the reaction represented by the reaction formula (2) occurs, producing ammonia (NH 3 ) and lithium hydride (LiH).
• This reaction between LiNH 2 and H 2 is performed by, for example, putting a container containing IiNH 2 in a furnace heated up to 300 0 C and then supplying hydrogen into the furnace at a pressure of 1 MPa (Refer to FIG 3).
• the reaction represented by the reaction formula (2) and its reverse reaction are reversible to each other, after NH 3 and LiH are produced by reacting LiNH 2 with H 2 , the produced NH3 and LiH then react with each other (i.e., the reaction represented by the reaction formula (2) occurs), whereby IiNH 2 and H 2 are produced. As a result, IiH is not produced, that is, the reverse reaction of the reaction represented by the reaction formula (2) does not occur.
• the NH 3 produced by the reaction between LiNH 2 and H 2 is collected using a filter, and the reverse reaction of the reaction represented by the reaction formula (2) is caused in the absence of NH3.
• the filter used for the collection of NH 3 is made of, for example, cooled activated carbon, or the like. In this case, liquid ammonia is collected by the activated carbon filter.
• the IiNH 2 produced in the second process S 12 contacts air, oxide films, or the like, are formed on the IiNH 2 , and this makes it difficult to react the LiNH 2 with H 2 . Therefore, in a case where IiH is regenerated using the above-described lithium hydride production method, the IiNH 2 produced in the second process S12 is preferably stored in a hermetically-sealed container, A container 1 shown in FIG 4A and FIG 4B is an example of such a container.
• FlG 4A shows the opened state of the container 1
• FIG 4B shows the closed state of the container 1.
• the container 1 is used to contain the LiNH 2 produced in the second process S12 and has an inner container 2 and an output container 3.
• the inner container 2 is made of stainless steel, or the like, and has a thickness of 0.5 to 1 ram or so
• the outer container 3 is made of a pressure-proof aluminum alloy, or the like.
• the inner container 2 is hermetically closed by a lid 5 having a valve 4 (refer to FIG 4B).
• the valve 4 is opened whereby the H 2 is collected from the inner container 2.
• the container 1 with the valve 4 closed is removed from the hydrogen production system incorporating the container 1 and then subjected to an LiH regeneration process. That is, the removed container 1 is put in a furnace in a regeneration process line shown in FIG 3. The temperature of the furnace is set to approx. 300 0 C. Then, H 2 is supplied into the container 1 at a pressure of, for example, 1 MPa. At this time, the H 2 is delivered into the inner container 2 via the valve 4 opened.
• the H 2 reacts with LiNH 2? whereby NH3 and LiH are produced.
• the NH3 produced in the container 1 is collected via other valve, not shown in the drawings, and thus only UH is left in the container 1.
• the container 1 with the valve 4 closed is removed from the LiH regeneration line, and then it is set again in the hydrogen production system, so that the LiH in the container 1 reacts with the NH 3 supplied via the valve 4, whereby hydrogen is produced.
• LiH can be regenerated by reacting the LiNH 2 produced in the second process S 12 with H 2 .
• the amount of the H 2 reacted with IiNH 2 in the above-described lithium hydride production method is very small as compared to the amount of the H 2 produced in the second process S 12. Therefore, the use of hydrogen for the above-described lithium hydride production (regeneration) does not affect the fact that the amount of hydrogen obtainable by the first hydrogen production method is large.
• the magnesium amide (Mg(NH 2 ⁇ ) produced in the second reaction process S22 is reacted with hydrogen (H2), whereby the reverse reaction of the reaction represented by the reaction formula (5) occurs, producing ammonia (NH 3 ) and magnesium hydride (MgH 2 ).
• This reaction between Mg(NH 2 ) 2 and H 2 is performed by, for example, putting a heat-proof container containing Mg(NH 2 ) 2 in a furnace heated up to 250 to 350 0 C and then supplying hydrogen into the furnace at a pressure of 0.5 to 2 Mpa.
• reaction represented by the reaction formula (5) and its reverse reaction are reversible to each other, after NHj and MgH 2 are produced by reacting Mg(NH 2 ) 2 with H 2 , the produced NH 3 and MgH 2 react with each other (i.e., the reaction represented by the reaction formula (5) occurs), whereby Mg(NH 2 ⁇ and H 2 are produced. As a result, MgH 2 is not produced, that is, the reverse reaction of the reaction represented by the reaction formula (5) does not occur.
• the NHj produced by the reaction between MgH 2 and H 2 is collected using a filter, and the reverse reaction represented by the reaction formula (5) is caused in the absence of NH 3 .
• the filter used for the collection of NH 3 is made of, for example, cooled activated carbon, or the like. In this case, liquid ammonia is collected by the activated carbon filer.
• the Mg(NH 2 ): produced in the second reaction process S22 contacts air, oxide films, or the like, are formed on the Mg(NH 2 ) 2 , and this makes it difficult to react the Mg(NH 2 ) 2 with H 2 . Therefore, in a case where MgH 2 is regenerated using the above-described magnesium hydride production method, the Mg(NH 2 ) 2 produced in the second reaction process S22 is preferably stored in a hermetically-sealed container, such as the container 1 shown in FIG 4.
• MgH 2 can be regenerated by reacting the Mg(NH 2 ) 2 produced in the second reaction process S22 with H 2 .
• the amount of the H 2 reacted with Mg(NH 2 ⁇ in the above-described magnesium hydride production method is very small as compared to the amount of the H 2 produced in the second reaction process S22. Therefore, the use of hydrogen for the above-described magnesium hydride production (regeneration) does not affect the fact that the amount of hydrogen obtainable by the second hydrogen production method is large.
• the lithium nitride (L1 3 N) regenerated by reacting nitrogen (N 2 ) with the lithium (Li) obtained from the lithium oxide (Li 2 O) produced in the third process S13 of the first hydrogen production method is used in the first process SIl.
• the method for obtaining Li from Li 2 O is not necessarily limited.
• Li may be obtained by reducing Li 2 O through molten-salt electrolysis.
• LijN can be regenerated by reacting Li obtained from Li 2 O produced in the third process S13 with N 2 .
• the reaction between Li and N 2 occurs under a mild condition, and therefore the regeneration of Li 3 N can be performed without using a large amount of energy.
• NH 3 and IiOH are produced by reacting L1 3 N with H 2 O in the first process SIl, and the NH3 produced in the first process SIl is reacted with LiH in the second process S12, whereby H 2 and LiNH 2 are produced, while the ⁇ OH produced in the first process SIl is reacted with LiH in the third process S13, whereby H 2 and Li 2 O are produced, Meanwhile, the lithium hydride production method regenerates IiH from the LiNH 2 produced in the second process S 12, and the lithium nitride production method regenerates L1 3 N from the Li 2 O produced in the third process S13.
• hydrogen can be produced using Li 3 N and IiH, and LiH and L1 3 N can be regenerated using the IiNH 2 and Li 2 O remaining after the production of hydrogen. Therefore, according to the hydrogen production method, the lithium hydride production method, and the lithium nitride production method of the first example embodiment, hydrogen production materials can be reused, which is very desirable for realizing a sustainable hydrogen society.
• the magnesium nitride (Mg 3 N 2 ) regenerated by reacting nitrogen (N 2 ) with the magnesium (Mg) obtained from the magnesium oxide (MgO) produced in the third reaction process S23 of the second hydrogen production method is used in the first reaction process S21.
• the method for obtaining Mg from MgO is not necessarily limited.
• Mg may be obtained by reducing MgO through molten-salt electrolysis.
• Mg3N 2 can be regenerated by reacting Mg obtained from MgO produced in the third reaction process S23 with N 2 .
• the reaction between Mg and N 2 occurs in a mild condition, and therefore the regeneration of Mg 3 N 2 can be performed without using a large amount of energy.
• NH3 and Mg(OH) 2 are produced by reacting Mg 3 N 2 with H 2 O in the first reaction process S21, and the NH 3 produced in the first reaction process S21 is reacted with MgH 2 in the second reaction process S22, whereby H 2 and Mg(NH 2 ) 2 are produced, while the Mg(OH) 2 produced in the first reaction process S21 is reacted with MgH 2 in the third reaction process S23, whereby H 2 and MgO are produced.
• the magnesium hydride production method regenerates MgH 2 using the Mg(NH 2 ) 2 produced in the second reaction process S22, while the magnesium nitride production method regenerates Mg 3 N 2 from the MgO produced in the third reaction process S23. Therefore, according to the hydrogen production method, the magnesium hydride production method, and the magnesium nitride production method of the second example embodiment, hydrogen can be produced using Mg 3 N 2 and MgH 2 , and MgH 2 and Mg 3 N 2 can be regenerated using the Mg(NH2)2 and MgO remaining after the production of hydrogen.
• FIG 5 schematically shows a hydrogen production system 10 according to the third example embodiment of the invention.
• the hydrogen production system 10 (will be referred to as "system 10" where necessary) implements the first hydrogen production method to produce hydrogen.
• the system 10 has a first tank 11 storing Li 3 N, a second tank 12 storing water, a third tank 13 storing LiH, a fourth tank 14 storing LiH, separating means 15 for separating NH 3 , a tank 16 containing: the first tank 11; the fourth tank 14; and separating means 15, and filters 17, 18.
• the first tank 11 and the second tank 12 are connected to each other via a line 51.
• the first tank 11, the separating means 15, and the third tank 13 are connected to each other via a line 52.
• the first tank Il and the fourth tank 14 are connected to each other via a line 53.
• the third tank 13 and the filter 17 are connected to each other via a line 54.
• the fourth tank 14 and the filter 18 are connected to each other via a line 55.
• the hydrogen production system 10 produces hydrogen
• water is supplied from the second tank 12 to the first tank 11, so that the reaction represented by the reaction formula (1) occurs between the supplied water and the L1 3 N stored in the first tank 11 (the first process SIl), whereby UOH and NH 3 are produced.
• the NH 3 produced in the first tank 11 is separated by the separating means 15 located at a position higher than the first tank 11 in the direction of gravity and made of activated carbon, or the like.
• the NH3 separated by the separating means 15 is delivered to the third tank 13 via the line 52.
• the reaction represented by the reaction formula (2) occurs between the LiH stored in the third tank 13 and the NH 3 delivered thereto (the second process S 12), whereby LiNH 2 and H ⁇ are produced.
• the H 2 produced in the third tank 13 is delivered to the filter 18 via the line 54, whereby impurities are removed.
• the LiNH 2 produced in the third tank 13 is kept in the third tank 13 and, for example, it is reformed into LiH using the lithium hydride production method described above.
• the LiOH produced in the first tank 11 is delivered separately, or together with the water supplied to the first tank 11, to the fourth tank 14 via the line 53.
• the fourth tank 14 is located at a position lower than the first tank 11 in the direction of gravity. Because LiH is stored in the fourth tank 14 to which the LiOH has been delivered, the reaction represented by the reaction formula (3) occurs between the LiH stored in the fourth tank 14 and the LiOH delivered (the third process S13), whereby Li 2 O and H 2 are produced.
• the H 2 produced in the fourth tank 14 is delivered to the filter 18 via the line 55, whereby impurities are removed.
• the Li 2 O produced in the fourth tank 14 is kept in the fourth tank 14. For example, it is reformed into IJ 3 N using the lithium nitride production method described above.
• FIG 6 schematically shows a hydrogen production system 20 according to the fourth example embodiment of the invention.
• the hydrogen production system 20 (will be referred to as "system 20" where necessary) implements the first hydrogen production method to produce hydrogen.
• the system 20 has a first tank 11 storing IJ 3 N, a second tank 12 storing water, a third tank 21 storing IiH, a fourth tank 14 storing UH, separating means 15 for separating NH3, a fifth tank 22 storing the separated NH 3 , and flow-controlling means 23 for controlling the flow of fluid between the first tank 11 and the fourth tank 14, a tank 16 containing: the first tank 11; the third tank 21; the fourth tank 14; separating means 15; and flow-controlling means 23, and filters 17, 18.
• the first tank 11 and the second tank 12 are connected to each other via a line 51.
• the first tank 11, the separating means 15, and the fifth tank 22 are connected to each other via a line 52.
• the first tank 11 and the fourth tank 14 are connected to each other via a line 53.
• the third tank 21 and the fifth tank 22 are connected to each other via a line 56.
• the third tank 21 and the filter 17 are connected to each other via a line 54.
• the fourth tank 14 and the filter 18 are connected to each other a line 55.
• the flow-controlling means 23 is disposed in the line 53. As long as the flow-controlling means 23 is closed, no fluid movement is allowed between the first tank 11 and the fourth tank 14 (e.g., LiOH and water are not allowed to move from the first tank 11 to the fourth tank 14).
• the reaction represented by the reaction formula (2) occurs between the LiH stored in the third tank 13 and the NfH 3 delivered thereto (the second process S 12), whereby LiNH 2 and H 2 are produced.
• the H 2 produced in the third tank 21 is delivered to the filter 17 via the line 54, whereby impurities are removed.
• the LiNH 2 produced in the third tank 21 is kept in the third tank 21. For example, it is reformed into LiH using the lithium hydride production method described above.
• the fourth tank 14 is located at a position lower than the first tank 11 in the direction of gravity, as the openings are formed at the flow-controlling means 23 due to the reaction represented by the reaction formula (2), the LiOH or the UOH and water present in the first tank 11 move to the fourth tank 14 via the openings at the flow-controlling means 23 provided in the line 53. Because LiH is stored in the fourth tank 14 to which the LiOH thus moves, the reaction represented by the reaction formula (3) occurs between the LiH stored in the fourth tank 14 and the LiOH moving thereto (the third process S 13), whereby Li 2 O and H 2 are produced. The H 2 produced in the fourth tank 14 is delivered to the filter 18 via the line 55, whereby impurities are removed. On the other hand, the Li 2 O produced in the fourth tank 14 is kept in the fourth tank 14. For example, it is reformed into Li 3 N using the lithium nitride production method described above.
• the delivery of LiOH from the first tank 11 to the fourth tank 14 may either be such that only solid LiOH is delivered from the first tank 11 to the fourth tank 14 or such that LiOH and water are delivered from the first tank 11 to the fourth tank 14.
• the solid LiOH and solid LiH react with each other, and therefore the reaction rate tends to be low. More specifically, when solid LiOH and solid LiH react with each other, the reaction rate of LiOH is 0.02 to 0.03 (g/sec/lkgH ⁇ ), and the usage rate of Li 3 N used when producing hydrogen through the reactions represented by the reaction formulas (1) to (3) is approx. 23 %.
• solid LiOH and solid LiH are preferably milled into particles measuring several tens nrn or so in size before reacted with each other.
• Using such LiOH particles and LiH particles for the reaction in the third process S 13 increases the contact area between the LiOH and the LiH as compared to when LiOH and LiH are not milled into particles in advance, and therefore the usage rate of LiaN increases up to approx. 65 %.
• the reaction represented by the reaction formula (3) is performed by supplying the LiOH and water in the first tank 11 to the fourth tank 14, the reaction rate LiOH is 0.1 to 0.3 (g/sec/lkgH2), and the usage rate of U 3 N is approx. 50 to 60 %.
• the third process S13 is preferably performed by supplying the IiOH and water in the first tank 11 to the fourth tank 14.
• LiH is stored in the third tank 13 of the system 10 and in the third tank 21 of the system 20, it is sufficient that at least LiH is stored in the third tank 13, 21, that is, whether other .materials should be stored in the third tank 13 and the third tank 21 is not specified.
• T1CI 3 is preferably stored in the third tank 13, 21 because it increases the reaction rate of the reaction represented by the reaction formula (2) and thus the yield of the hydrogen produced through said reaction.
• LiH is stored in the fourth tank 14 of the system 10 and the fourth tank 14 of the system 20, it is sufficient that at least LiH is stored in the fourth tank 14, and therefore, whether other materials should be stored in the fourth tank 14 is not specified.
• TiCb is preferably stored in the fourth tank 14 in addition to LiH because it increases the reaction rate of the reaction represented by the reaction formula (3) and thus the yield of the hydrogen produced through said reaction and it also reduces the temperature required to ensure smooth progression of said reaction.
• a hydrogen production system 30 according to the fifth example embodiment of the invention implements the second hydrogen production method to produce hydrogen.
• the basic structure of the system 30 is the same as that of the system 10 described above, and therefore the reference numerals for the respective components and parts of the system 30 are indicated in parentheses in FIG 5. Hereinafter, the system 30 will be described with reference to FlG 5.
• the system 30 has a first tank 31 storing M ⁇ N 2 , a second tank 32 storing water, a third tank 33 storing MgH 2 , a fourth tank 34 storing MgH 2 , separating means 35 for separating NH 3 , a tank 36 containing: the first tank 31; the fourth tank 34; and separating means 35, and filters 37, 38.
• the first tank 31 and the second tank 32 are connected to each other via a line 51.
• the first tank 31, the separating means 35, and the third tank 33 are connected to each other via a line 52.
• the first lank 31 and the fourth tank 34 are connected to each other via a line 53.
• the third tank 33 and the filter 37 are connected to each other via a line 54.
• the fourth tank 34 and the filter 38 are connected to each other via a line 55.
• the reaction represented by the reaction formula (5) occurs between the MgH 2 stored in the third tank 13 and the NH 3 delivered thereto (the second reaction process S22), whereby Mg(NH 2 ) 2 and H 2 are produced.
• the H 2 produced in the third tank 33 is delivered to the filter 37 via the line 54, whereby impurities are removed.
• the Mg(NH 2 ⁇ produced in the third tank 33 is kept in the third tank 33 and, for example, it is reformed into MgH 2 using the magnesium hydride production method described above.
• the Mg(OH) 2 produced b the first tank 31 is delivered separately, or together with the water supplied to the first tank 31, to the fourth tank 34 via the line 53.
• the fourth tank 34 is located at a position lower than the first tank 31 in the direction of gravity. Because MgH 2 is stored in the fourth tank 34 to which the Mg(OH) 2 has been delivered, the reaction represented by the reaction formula (6) occurs between the MgH 2 stored in the fourth tank 34 and the Mg(OH) 2 delivered thereto (the third reaction process S23), whereby MgO and H 2 are produced.
• the H 2 produced in the fourth tank 34 is delivered to the filter 38 via the line 55, whereby impurities are removed.
• the MgO produced in the fourth tank 34 is kept in the fourth tank 34.
• it is reformed into Mg 3 N 2 using the magnesium nitride production method described above.
• hydrogen is produced through the first reaction process S21 to the third reaction process S23.
• a hydrogen production system 40 according to the sixth example embodiment of the invention implements the second hydrogen production method to produce hydrogen.
• the basic structure of the system 40 of the sixth example embodiment is the same as that of the system 20 described above, and therefore the reference numerals for the respective components and parts of the system 40 are indicated in parentheses in FIG 6. Hereinafter, the system 40 will be described with reference to FIG 6.
• the system 40 has a first tank 31 storing Mg 3 N 2 , a second tank 32 storing water, a third tank 41 storing MgH 2 , a fourth tank 34 storing MgH 2 , separating means 35 for separating NH3, a fifth tank 42 storing the separated NH 3 , and flow-controlling means 43 for controlling the flow of fluid between the first tank 31 and the fourth tank 34, a tank 36 containing: the first tank 31; the third tank 41; the fourth tank 34; separating means 35; and flow-controlling means 43, and filters 37, 38.
• the first tank 31 and the second tank 32 are connected to each other via a line 51.
• the first tank 31, the separating means 35, and the fifth tank 42 are connected to each other via a line 52.
• the first tank 31 and the fourth tank 34 are connected to each other via a line 53.
• the third tank 41 and the fifth tank 42 are connected to each other via a line 56.
• the third tank 41 and the filter 37 are connected to each other via a line 54.
• the fourth tank 34 and the filter 38 are connected to each other a line 55.
• the flow-controlling means 43 is disposed in the line 53. As long as the flow-controlling means 43 is closed, no fluid movement is allowed between the first tank 31 and the fourth tank 34 (e.g., Mg(OH) 2 and water are not allowed to move from the first tank 31 to the fourth tank 34).
• the reaction represented by the reaction formula (5) occurs between the MgH 2 stored in the third tank 41 and the NH 3 delivered thereto (the second reaction process S22), whereby Mg(NH 2 ). and H 2 are produced.
• the H 2 produced in the third tank 41 is delivered to the filter 37 via the line 54, whereby impurities are removed.
• the Mg(NH 2 ) 2 produced in the third tank 41 is kept in the third tank 41. For example, it is reformed into MgH 2 using the magnesium hydride production method described above.
• the fourth tank 34 is located at a position lower than the first tank 31 in the direction of gravity, as the openings are formed at the flow-controlling means 43 due to the reaction represented by the reaction formula (5), the Mg(OH) 2 and water present in the first tank 31 move to the fourth tank 34 via the openings at the flow-controlling means 43 provided in the line 53. Because MgH 2 is stored in the fourth tank 34 to which the Mg(OH) 2 thus moves to, the reaction represented by the reaction formula (6) occurs between the MgH 2 stored in the fourth tank 34 and the Mg(OH) 2 moving thereto (the third reaction process S23), whereby MgO and H 2 are produced.
• the H 2 produced in the fourth tank 34 is delivered to the filter 38 via the line 55, whereby impurities are removed.
• the MgO produced in the fourth tank 34 is kept in the fourth tank 34. For example, it is reformed into Mg 3 N 2 using the magnesium nitride production method described above. [0092] As such, as the system 40 implements the second hydrogen production method such that the second reaction process S22 is performed after the first reaction process S21 and the third reaction process S23 is performed after the second reaction process S22, hydrogen is produced in the second reaction process S22 and the third reaction process S23.
• the invention is not limited to this feature.
• the third reaction process S23 may be performed by delivering only the solid Mg(OH) 2 remaining in the first tank 31 to the fourth tank 34, In this case, however, because solid Mg(OH) 2 and solid MgH 2 react with each other, the reaction rate tends to be low.
• solid Mg(OH) 2 and solid MgH 2 react with each other, the reaction rate of Mg(OH) 2 is 0.01 to 0.03 (g/sec/lkgH 2 ), and the usage rate of Mg 3 N 2 for the reactions represented by the reaction formulas (4) to (6) is approx. 15 to 20 %. Therefore, in a case where hydrogen is produced by reacting solid Mg(OH) 2 with solid MgH 2 , in order to improve the usage rate of Mg 3 N 2 , solid MgH 2 and solid Mg(OH) 2 are preferably milled into particles measuring several tens nm or so in size before reacted with each other.
• MgH 2 particles and Mg(OH) 2 particles for the reaction in the third reaction process S23 increases the contact area between MgH 2 and Mg(OH) 2 as compared to when MgH 2 and solid Mg(OH) 2 are not milled into particles in advance, and therefore the usage rate of Mg 3 N 2 increases up to approx. 30 to 35 %.
• the third reaction process S23 is performed by supplying the Mg(OH) 2 and water in the first tank 31 to the fourth tank 34, the reaction rate of Mg(OH) 2 is 0.07 to 0.1 (g/sec/lkgH 2 ), and the usage rate of Mg 3 N 2 is approx. 40 to 55 %.
• the reaction represented by the reaction formula (6) is preferably caused by supplying the Mg(OH) 2 and water in the first tank 31 to the fourth tank 34.
• MgH 2 is stored in the third tank 33 of the system 30 and jn the third tank 41 of the system 40, it is sufficient that at least MgH 2 is stored in the third tank
• T1CI 3 is preferably stored in the third tank 33, 41 in addition to MgH 2 because it increases the reaction rate of the reaction represented by the reaction formula (5) and thus increases the yield of the hydrogen produced through said reaction.
• MgH 2 is stored in the fourth tank 34 of the system 30 and the fourth tank 34 of system 40, it is sufficient that at least MgH 2 is stored in the fourth tank
• TiCl 3 is preferably stored in the fourth tank 34 in addition to MgH 2 because it increases the reaction rate of the reaction represented by the reaction formula (6) and thus increases the yield of the hydrogen produced through said reaction and it also reduces the temperature required to ensure smooth progression of said reaction.
• the supplying of water to the first tank to perform the first process or the first reaction process may be performed in various manners. However, if a large amount of water is supplied to the first tank, it causes a rapid temperature increase and thus increases the pressure of ammonia, which may result in production of a mixture gas of ammonia and water vapors. In view of preventing this, preferably, water is gradually supplied to the first tank at a low rate or cooled water is supplied to the first tank.
• FIG 7 schematically shows a fuel cell system 100 according to the seventh example embodiment of the invention.
• the components and parts identical to those shown in FIG 6 are denoted by the same reference numerals and therefore they are not described again.
• the fuel cell system 100 will hereinafter be described with reference to FIG 7.
• the fuel cell system 100 has a fuel cell module 70 constituted of a plurality of fuel cells (not shown in the drawings) and a hydrogen production system 20.
• the fuel cell module 70 and the hydrogen production system 20 are connected to each other via a line 55 and a line 60.
• the hydrogen produced by the hydrogen production system 20 is delivered to the fuel cell module 70 via the line 55 and then to the anodes of the respective fuel cells of the fuel cell module 70.
• Water is produced as the fuel cell module 70 generates electric power from the hydrogen supplied to the anodes of the respective fuel cells and the air supplied to the cathodes of the respective fuel cells.
• the water is filleted by a filter 61 provided in the line 60 to remove the impurities contained therein and then delivered to the second tank 12.
• the water is then delivered to the first tank 11 via the line 51 and used to produce hydrogen.
• the hydrogen produced by the hydrogen production system 20 is supplied to the fuel cell module 70, and the fuel cell module 70 operates using the supplied hydrogen, and the water produced through the operation of the fuel cell module 70 is then supplied to the second tank 12 to produce hydrogen.
• hydrogen production materials can be reused.
• the fuel cell system 100 has the hydrogen production system 20, it may alternatively have other hydrogen production system, such as the hydrogen production system 10, 30, or 40.
• the reactions represented by the reaction formulas (3) and (6) are rate-determining reactions and their reactions rates increase at a high temperature, if the third process S13 and the third reaction process S23 are performed after the second process S 12 and the second reaction process S22, respectively, the time needed for hydrogen production through the reaction represented by the reaction formula (3) and the time needed for hydrogen production through the reaction represented by the reaction formula (6) become shorter, and therefore the hydrogen production efficiency improves accordingly.
• the hydrogen production system 20 or the hydrogen production system 40 is preferably incorporated in the fuel cell system 100.
• the masses of lithium nitride, water, and so on, provided in the hydrogen production system 20 of the fuel cell system 100 are not necessarily limited.
• the hydrogen production system 20 is only required to have 625 mol of lithium nitride, 2500 mol of lithium hydride, and 1875 mol of water.
• the dimensions of the hydrogen production system 20 of the fuel cell system 100 are not necessarily limited.
• a tank having a capacity of approx. 170 Land a weight of approx. 160 kg may be used as the tank 16.
• LiH was stored in the third tank 21 and the fourth tank 14 as follows. First, IiH was weighed using a glove box containing an argon atmosphere (dew point: -85 0 C, oxygen concentration: 1 ppm or lower), and the LiH was put in a milling container. Then, the milling container was vacuumed, and then a hydrogen atmosphere (1 MPa) was formed in the milling container. Then, ball milling was performed at a room temperature for 10 hours. Then, the milling container was moved into the glove box containing an argon atmosphere, and the milled LiH was put in the third tank 21 and the fourth tank 14 in the globe box.
• argon atmosphere dew point: -85 0 C, oxygen concentration: 1 ppm or lower
• LiH and TiCl 3 were put in the third tank and the fourth tank of the system 20' as follows.
• the third tank and the fourth tank of the system 20' will hereinafter be referred to as "the third tank 21'" and “the fourth tank 14'", respectively.
• the rate (reaction rate) of hydrogen production by the reaction represented by the reaction formula (2) at 20 0 C in the system 20 was 0.1 to 0.3 [g/sec].
• the rate (reaction rate) of hydrogen production by the reaction represented by the reaction formula (2) at 20 0 C in the system 20' was 0.5 to 1 [g/sec].
• the rate (reaction rate) of hydrogen production by the reaction represented by the reaction formula (3) at 200 0 C in the system 20 was 0.02 to 0.03 [g/sec].
• the rate (reaction rate) of hydrogen production by the reaction represented by the reaction formula (3) at 200 0 C in the system 20' was 0.05 to 0.1 [g/sec].
• the yield of hydrogen produced by the reaction represented by the reaction formula (2) at 25 0 C in the system 20 was approx. 65 to 75 %.
• the yield of hydrogen produced by the reaction represented by the reaction formula (2) at 25 0 C in the system 20' was 80 to 85 %.
• the yield of hydrogen produced by the reaction represented by the reaction formula (3) at 250 0 C in the system 20 was approx. 65 to 75 %.
• the yield of hydrogen produced by the reaction represented by the reaction formula (3) at 180 0 C in the system 20' was 80 to 85 %.
• a target hydrogen production rate X for hydrogen production by the reaction represented by the reaction formula (3) was achieved in a thermal condition of around 250 0 C.
• the target hydrogen production rate X for hydrogen production by the reaction represented by the reaction formula (3) was achieved in a thermal condition of around 180 0 C.
• the "after the first process” in the present invention may be meant as "after the ammonia to be reacted in the second process has been produced in the first process", or "after the hydroxide of the metal to be reacted in the third process has been produced in the first process".
• the second process and the third process may be performed after the end of the first process, or the second process and/or the third process may be performed during the first process.

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• 2008
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